An SDN is a new and innovative network architecture proposed originally by the clean slate research group at the Stanford University. The OpenFlow protocol, the core technology of the SDN, separates the control plane of a network device (including an OpenFlow controller) from the data plane of the network device (including an OpenFlow switch, i.e. the OpenFlow forwarding device), therefore, the network traffic can be controlled flexibly, and a good platform is provided for the core network and the innovation of its application.
As shown in FIG. 1, it is a schematic diagram showing application of an OpenFlow protocol and an OpenFlow configuration protocol in the related art. The OpenFlow protocol is used to describe the standard of information used by the interaction between OpenFlow controllers and OpenFlow forwarding devices, and the interface standard between controllers and forwarding devices. The OpenFlow protocol also supports a Group Table, as shown in Table 1 that shows the content of a Group Table in the related art.
TABLE 1Group IdentifierGroup TypeCountersAction Buckets
In Table 1 above, the group identifier identifies the group table. When the Group Type is all, the group table is used in forwarding multicast and broadcast flows. The Action Buckets are lists of multiple Action Sets. The forwarding process of a multicast packet in the OpenFlow protocol is: when the forwarding device (for example, the OpenFlow forwarding device) receives the multicast packet, a Flow Entry in the flow table is first matched according to the source address and the group address in the multicast packet. After the matching is successful, an Action Set in the Flow Entry may execute the “Group group-id” command, so that a group table processing is further performed on the multicast packet. When it is found that the Group Type is all after entering of the group table, the multicast packet is copied for each action bucket respectively so as to be executed. After the execution is finished, the multicast packets are forwarded out from multiple egress interfaces of the action buckets, thereby finishing the forwarding of the multicast packet. However, the foregoing forwarding manner of the multicast packet based on the OpenFlow group table is a forwarding manner which is based on the flow, that is, a Source Internet Protocol address (also referred to as S-IP) and a destination group IP address (abbreviated as: G-IP), that is, the (S, G) flow table and the group table, need to be created for each flow on each forwarding device. In a case that the topology of a multicast network remains unchanged, the more the multicast flows, the larger the entries, thus wasting the entry space extremely.
In summary, the space occupied by entries is relatively large and the forwarding efficiency is relatively low because it is necessary to establish a corresponding flow table and a corresponding group table for each flow on each forwarding device when the multicast pocket is forwarded using the related OpenFlow technology.